The present invention generally relates to refrigeration systems. More particularly, this invention relates to a vapor-compression-cycle refrigeration system having a Peltier condenser.
Vapor-compression-cycle refrigeration systems, widely known in the art, generally comprise an evaporator in which liquid refrigerant boils at low temperature to produce cooling, a compressor which raises the pressure and temperature of the gaseous refrigerant, a condenser in which the refrigerant discharges its heat to the environment, a receiver which stores the liquid condensed in the condenser, and an expansion valve through which the liquid refrigerant expands from the high-pressure level in the condenser to the low-pressure level in the evaporator. Prior art condensers for vapor-compression-cycle refrigerators may be air-cooled for small- and medium-capacity cooling, or water-cooled, as in shell-and-tube, shell-and-coil, or double-pipe type condensers, for large capacity cooling.
Air-cooled condensers are limited by fluctuations in the temperature of ambient air used to cool the refrigerant. Higher ambient air temperature reduces the cooling capacity of the condenser. Compressor efficiency is thereby decreased and the compressor is required to run longer, increasing the load on the compressor motor and the electricity requirements. Furthermore, the life of the compressor is therefore reduced as a result of temperature fluctuations in ambient air. Air-cooled condensers also become less efficient as heat is extracted from the refrigerant since ambient temperature determines the rate of heat extraction and becomes hotter as heat is withdrawn from the refrigerant. Evaporator condensers, a device combining a condensing coil and a forced-draft cooling tower in a single unit, are also known in the prior art.
In large capacity refrigeration systems, particularly commercial refrigeration systems utilizing water-cooled condensers, large quantities of condensing water are required to discharge heat from the high pressure gaseous refrigerant. These large amounts of water are often wasted to a drain or the like. In many locales water is a scarce and expensive commodity and its use may be limited by law. To prevent this wastage of water, cooling towers and spray ponds are commonly used to re-cool water for reuse. Cooling towers and spray ponds greatly increase the maintenance requirements of a refrigeration system and may require the addition of water treatment facilities. Thermal pollution of lakes and streams has been known to occur where systems of this type are utilized. Water-cooled condensers also become less efficient over time due to corrosive particles generally found in tap water. Rupture problems are also common for water-cooled condensers which results in contamination and water-fouling problems. Such problems shorten the life of a refrigeration system and result in the use of even greater amounts of water.
To overcome the above-mentioned limitations of prior art refrigeration systems utilizing air-cooled and water-cooled condensers the present invention discloses a vapor-compression-cycle refrigeration system utilizing thermoelectric cooling in the condenser.
Thermoelectric cooling, more widely referred to as Peltier cooling, is known in the prior art. However, the Peltier cooling systems of the prior art generally operate by providing means to directly cool the interior of a cooling chamber (in lieu of the evaporator in vapor-compression-cycle refrigeration systems) using the Peltier effect of semiconductors. In the prior art, Peltier cooling is generally understood as a more expensive and less efficient alternative to standard vapor-compression-cycle refrigerators. Their use is largely restricted to situations in which lower maintenance, increased life, or quiet performance are essential, or in situations, such as in space vehicles or artificial satellites, in which the vapor-compression-cycle refrigerators are impractical.
Peltier cooling is also known in the art for localized cooling of electronic components, such as integrated circuits, power transistors, lasar diode IR detectors and solid state imaging devices, for use in Peltier thermostats in precision radiometers and photometers, and for cooling moderate volumes of air or other gases to serve the same function as the evaporator coil in a conventional air-conditioner design.
U.S. Pat. No. 3,037,358 to Scofield and U.S. Pat. No. 3,073,126 to Staebler disclose a refrigeration apparatus in an air conditioner that makes ice by Peltier cooling as an auxiliary function. Integrated comfort conditioning systems are shown in U.S. Pat. Nos. 3,403,723 and 3,488,971 to Meckler which include Peltier cooling for transferring heat to circulating water. U.S. Pat. No. 4,290,273 to Meckler discloses a chiller and heat pump system that employs a Peltier effect diffusion still.
No prior art reference known to the Applicant discloses or suggests a vapor-compression-cycle refrigerator that incorporates Peltier cooling to discharge heat from a gaseous refrigerant for condensation of the refrigerant.